Most fireworks or pyrotechnics displays launch projectiles or pyrotechnic effects from launch tubes including one-use disposable cardboard tubes. Pyrotechnic projectiles may be loaded with fireworks effects adjacent to or packed within a dispersive explosive.
Likewise, there may be one or more such as multiple projectiles (pyrotechnic effects) that may be propelled from a launch tube upon the ignition of a launch charge (lift charge). These projectiles or pyrotechnic effects may include many different types of effects such as stars that produce colored or spark effects, hummers, whistles, flash, and the like. The pyrotechnic device that propels from a mortar several stars or pyrotechnic effects may be called “mines” or “star mines.”
Herein, the terms or phrase “multiple pyrotechnic projectiles or multiple pyrotechnic effects” may be collectively referred to as “effects.”
In conventional operation of a mine, upon detonation of a lift charge within a launch tube (mortar), effects may be launched out of the tube as a result of explosive gas emanation from the launch tube as a result of the detonation. The manner of delivery into the air of effects may depend strongly on the behavior of detonation of the lift charge and the flow of gases produced thereby.
Subsequent to the lift charge explosion, the effects are ignited by the heat and fire of the explosive gas emanation out of the launch tube and the effects are further propelled along with the gases out of the launch tube and subsequently produce a typical visual pyrotechnic effect, such as one or more of colorful, sparkling, flash, sound, and/or streaming effects.
The effects come in many different shapes and sizes, but all are typically launched from a mortar launcher (such as a launch tube) by a lift charge, which may be contained in a lift charge container within the launch tube. For example, one suitable low-smoke producing launching system that may be used is found in U.S. Pat. No. 9,062,943, the disclosure of which is hereby incorporated by reference herein in its entirety.
Another suitable low-smoke producing launching system that may be used is found in U.S. Pat. No. 9,217,624 “Spooling pyrotechnic device” which is hereby fully incorporated herein by reference.
Several factors contribute to the effects being successfully raised to a desired selected altitude and with an aesthetic dispersion e.g., a symmetric pyrotechnic effect display. For example, the type and amount of lift charge used to propel the effects, the size and weight of the effects, the shape of the effects are some of the many factors that may be desirably controlled.
The dispersion of effects is described as the “pattern of display.” Typically, an aesthetic pattern of display may be one where the projectiles or pyrotechnic effects have a symmetrical grouping.
A non-aesthetic pattern of display may be a pattern of display where the projectiles or pyrotechnic effects have a non-symmetrical grouping.
Examples of an aesthetic pattern of display may result when the effects are each propelled from the tube launcher with similar velocities.
Examples of a non-aesthetic pattern of display may be when the individual effects are propelled from the tube launcher or mortar with a wide range of velocities.
One problem associated with either a contained lift charge designed to burst a container upon ignition (see U.S. Pat. Nos. 9,062,943 and 9,217,624) or an uncontained lift charge such a black powder, is adequate control over the behavior of the effects discharged out of the launch tube upon ignition of the lift charge. In particular, it may be difficult to control the desired delivery of the effects due to non-uniformity (e.g., non-laminarity) of gas flow emanating as a result of ignition and explosion of the lift charge within the launch tube. A poor delivery of the effects caused by the relative turbulence or non-laminarity of the gas flow may produce a non-aesthetic (e.g., non-symmetric) pattern of display.
Another significant problem with prior art systems including the expulsion of effects into the air includes debris fallout associated with the lift charge detonation and/or debris associated with propelling the effects out of the mortar and/or the main burst including secondary detonation and burning.
Therefore there is a continuing need in the art to provide improved delivery of pyrotechnic effects from a launch tube with improved control over projectile launch behavior and with reduced debris fallout.
It is therefore among the objects of the invention to provide an improved device and method for delivery of pyrotechnic effects from a launch tube with improved control over projectile launch behavior and with reduced debris fallout.
These and other objects, aspects and features of the invention will be better understood from a detailed description of embodiments of the invention which are further described below in conjunction with the accompanying Figures.